PSU Suggestion for GTS 450

I have recently ordered a new GTS 450 - EVGA GeForce GTS 450 FPB (Free Performance Boost)
EVGA | Products

Please suggest a entry level PSU for the following config

CPU: Intel Pentium(R) Dual-Core CPU E5300 @ 2.60GHz
MBoard: ASUS P5KPL-AM/PS
Memory: 2 x 2GB Transcend DDR2
Display: Acer V233H @ 1920x1080

Current GPU: ATI Radeon HD 4350
Current SMPS: Mercury 400W

I know its a out dated config, but can't afford a CPU upgrade rite now.

My budget is max 3k, I was looking at Corsair CX500, but I could a CX430 @ 2.2k, I am not sure if CX430 will support GTS 450

Please provide your suggestions.

Thanks,
Krishna